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When you woke up this morning, what did you do first?

Did you hop in the shower, check your email or grab a doughnut? What did you say to your roommates on the way out the door? Salad or hamburger for lunch? When you got home, did you put on your sneakers and go for a run, or eat dinner in front of the television?

Most of the choices we make each day may feel like the products of well-considered decision making, but they’re not. They’re habits. And though each habit means relatively little on its own, over time, the meals we eat, how we spend our evenings, and how often we exercise have enormous impacts.

This is particularly true in our 20s, when so many of our habits are still up for grabs. The patterns you establish right now will impact your health, productivity, financial security and happiness for decades. How much money you make, how much time you spend with your friends and family, how well your body functions years from now — all of these, in many ways, are products of the habits you are building today.

And in the last decade, our understanding of the neurology of habit formation has been transformed. We’ve learned how habits form — and why they are so hard to break. We now know how to create good habits and change bad ones like never before.

At the core of every habit is a neurological loop with three parts: A cue, a routine and a reward.

To understand how to create habits — such as exercise habits — you must learn to establish the right cues and rewards.

In 2002, researchers at New Mexico State University studied 266 individuals, most of whom worked out at least three times a week. They found that many of them had started running or lifting weights almost on a whim, or because they suddenly had free time or wanted to deal with unexpected stresses in their lives.

However, the reason they continued exercising — why it became a habit — was because of a specific cue and a specific reward.

If you want to start running each morning, it’s essential that you choose a simple cue (like always lacing up your sneakers before breakfast or always going for a run at the same time of day) and a clear reward (like a sense of accomplishment from recording your miles, or the endorphin rush you get from a jog). But countless studies have shown that, at first, the rewards inherent in exercise aren’t enough.

So to teach your brain to associate exercise with a reward, you need to give yourself something you really enjoy — like a small piece of chocolate — after your workout.

This is counterintuitive, because most people start exercising to lose weight. But the goal here is to train your brain to associate a certain cue (“It’s 5 o’clock”) with a routine (“Three miles down!”) and a reward (“Chocolate!”).

Eventually, your brain will start expecting the reward inherent in exercise (“It’s 5 o’clock. Three miles down! Endorphin rush!”), and you won’t need the chocolate anymore. In fact, you won’t even want it. But until your neurology learns to enjoy those endorphins and the other rewards inherent in exercise, you need to jump-start the process.

And then, over time, it will become automatic to lace up your jogging shoes each morning. You won’t want the chocolate anymore. You’ll just crave the endorphins. The cue, in addition to triggering a routine, will start triggering a craving for the inherent rewards to come.